1. Field of the Invention
This invention relates to aliphatic diamines, and more particularly to aromatic-aliphatic diamines containing no hydrogen atoms beta to the central arylene group or to the amino groups. This invention also relates to stable, rigid polymers derived from said diamines.
2. Description of the Art
Neopentyl diamine is known and polyamides have been made from this diamine. No aromatic bis(neopentylamine) has been found in the art.
U.S. Pat. No. 2,497,673 to Kirk Jr. (I) discloses diamines of the formula ##STR3## wherein Ar includes certain of the Ar groups described in the instant application.
U.S. Pat. No. 2,464,693 to Kirk Jr. (II) discloses diamines of the formula ##STR4## wherein Ar includes certain of the Ar groups described in the instant application.
U.S. Pat. No. 2,900,369 to Edwards et al discloses a diamine having the formula ##STR5##
U.S. Pat. No. 3,422,143 to Bottomley discloses diamines of the formula ##STR6## where R.sup.1 and R.sup.2 are lower alkyl, R.sup.3 and R.sup.4 are hydrogen or lower alkyl wherein Ar includes certain of the Ar groups described in the instant application.
The above-cited patents disclose homologs and an isomer of the diamines of this invention. These known diamines have the general formula ##STR7## wherein n is 0, 1, 2 or 4. All of these diamines contain hydrogen atoms in positions beta to arylene or to nitrogen, or both. Such diamines provide polymers which are demonstrably inferior in thermal stability to polymers prepared from diamines of this invention which contain no hydrogen atoms beta to either arylene or nitrogen. In this regard see the Comparative Examples preceding the claims.
British Pat. No. 799,762 to Bataafsche discloses diamines of the formula ##STR8## where R.sub.2 represents the same or different alkyl groups of 1 to 6 carbon atoms, and X represents an alkylene group containing 2 to 5 carbon atoms. All of the "X" alkylene groups actually disclosed are straight chain alkylene groups containing only repeating --CH.sub.2 -- groups; such diamines contain hydrogen atoms beta to both arylene and nitrogen. Finally, this patent contains no enabling disclosure for preparing the diamines of the instant invention.
U.S. Pat. No. 3,175,007 to Berhenke discloses various dianilines which are diamines of the formula ##STR9## where --X-- is --O--, --S--, ##STR10## or a lower alkylidene radical. One disclosed compound, methylenedianiline (column 2, line 23), is without aliphatic beta hydrogen atoms but is completely different structurally from the diamines of the instant invention.